If you spot something large and bright moving across the night sky, you almost certainly have not discovered a new star.

What you will probably have seen is the recently launched International Space Station (ISS) complete with its new solar wings.

You'll know when you've picked it up because it's a steadily shining, moving object

Astronomer Dennis Ashton, Sheffield Hallam University

The installation of the giant electricity-generating panels over the weekend should make the orbiting craft one of the brightest objects in the firmament.

The new power system weighs 17 tonnes - its wings measure 73 metres (240 feet) across, a longer span than a Boeing 777 airliner.

The solar panels are designed to boost the station's power supply fivefold, providing the platform with sufficient electricity to run all of its current modules and one or two yet to arrive.

But they will also make the station much bigger, brighter and - given favourable conditions - easier to see from Earth, 376km (235 miles) away.

When to see it

Astronomers say the best times to view the new heavenly body are within an hour or two before sunrise or after sunset, when the sky is dark but the space station is sunlit.

The ISS is in urgent need of extra power

The ISS orbits the Earth roughly every 90 minutes, or about 16 times a day, travelling from west to east.

Dennis Ashton, director of the Star Centre at Sheffield Hallam University, UK, said the vessel should be easy to spot with the naked eye.

He said Britain could expect good views in the second half of December, and particularly good ones on Christmas Eve.

Mr Ashton said the ISS should look just like a bright star, depending on the angle of view and the amount of reflected sunlight.

Easy to spot

"It's quite clear to see," he told the BBC Today programme. "You'll know when you've picked it up because it's a steadily shining, moving object.

"We've got a wonderful background to it because over in the west we've got bright Venus shining like a Christmas star and then over in the east, Jupiter and Saturn are coming up."

Astronomers say the space station will rival the bright star Sirius, or perhaps the planet Venus, when the angles for viewing it are favourable.

Those who have known where to look have actually been able to see the space station for some time. But the addition of the giant solar panels is sure to make the station an unmissable presence from now on.

Whatever your location on Earth, you can find the ISS in the sky by using one of the many position calculators posted on websites. See the internet links in the right-hand navigation on this page.